Transmission Not Shifting Into 3rd When Lights Are On.

[cnctony]

My 93 LS400 starts and drives fine, hot or cold. Long drive or short. When I drive at night or during the day, if I turn the LIGHTS ON the car will not get out of 2nd gear. If I turn the lights off it will shift and run fine, but it's hard to see the road in the dark. I tried changing the battery and checked the battery cables and connections.

I took to local mechanic and he said the tranny is fine and I needed to replace the ECM? module.

Where is it at and does that sound like the problem? I don't want to keep buying parts and not fix the problem especially if they are expensive and non-returnable electrical items.

Any thoughts?

Thanks.

Anthony

84 BMW 318I

88 Mercedes Benz 300

93 LS 400

96 Grand Caravan

98 ZX2

My cylinder index is rising. "35"

[obergc]

Anthony, to make a long story short, have your mechanic get a voltmeter on the transmission gear selector solenoid circuits at the transmission input and then check again with the lights on. If you are finding strange voltage inputs into the solenoid circuitry when you shouldn't, first thing I would check would be for broken wiring in the trunk, left hinge area. Broken wires in the trunk hinge area are very common and the trunk wiring ties into the gear selector lights inside the instrument cluster and they in turn tie into the transmission solenoids through the gear selector switch. I inadvertently found that the transmission solenoid selector circuits had voltage riding on them all the time, even when they weren't selected when I installed an automatic door lock system in my 93, with the doors locking when reverse was selected. At first I had problems with the automatic door locks until I discovered the "stray" voltage on the gear selector circuits. Won't hurt to check it out and it could save you some big bucks.

[SKperformance]

One might want to search threads for trunk wires that break in the hinge arm.

[cnctony]

One might want to search threads for trunk wires that break in the hinge arm.

WOW I had no idea. I tried searching for a thread about this topic but foud either way to many or nothing specific to my problem . I will visually inspect tonight. If I get time and let you know. Otherwise it will be next week.

THANKS A BUNCH! And MERRY CHRISTMAS TO ALL AND TO ALL A GOODNIGHT.

Thanks.

Anthony

84 BMW 318I

88 Mercedes Benz 300

93 LS 400

96 Grand Caravan

98 ZX2

My cylinder index is rising. "35"

[CUMan]

You may not find any discussions on the trunk hinge broken wire problem that are specific to your situation. The strange thing about this problem is that it causes numerous different electrical problems. Illumination of the "R" in the transmission gear indicator seems to be very common, but the other problems seem to vary significantly from one affected car to another.

When this problem occurred in my 93 LS, the inside trunk release would not open the trunk. Also, the transmission seemed to shift differently. The most weird part was that the brakes felt strange, like they were grabbing instead of applying smoothly. I have no idea how an electrical problem could cause the brakes to feel strange.

[92ls forhundo]

i think that 2 0r 3 years ago that this system servers crashed and all info up to that point was lost, from what i gather their was info on the trunk bundle that was lost when that happened. By that same token i cant use the inside trunk release on my trunk, however ive never had a master key so maybe the valet lock is just locked.

[SKperformance]

here is oa few

http://us.lexusownersclub.com/forums/index...=24822&hl=hinge

http://us.lexusownersclub.com/forums/index...=17492&hl=hinge

http://us.lexusownersclub.com/forums/index...?showtopic=3821

[finstratin]

On New Years Day, you just made my year with your great advice. Sure enough, my LS400 wouldn't shift out of first gear and sure enough, I found 2 broken wires in the trunk wiring harness! Cleared check engine codes and shifts like new again!

Thanks!

Finstratin

My 93 LS400 starts and drives fine, hot or cold. Long drive or short. When I drive at night or during the day, if I turn the LIGHTS ON the car will not get out of 2nd gear. If I turn the lights off it will shift and run fine, but it's hard to see the road in the dark. I tried changing the battery and checked the battery cables and connections.

I took to local mechanic and he said the tranny is fine and I needed to replace the ECM? module.

Where is it at and does that sound like the problem? I don't want to keep buying parts and not fix the problem especially if they are expensive and non-returnable electrical items.

Any thoughts?

Thanks.

Anthony

84 BMW 318I

88 Mercedes Benz 300

93 LS 400

96 Grand Caravan

98 ZX2

My cylinder index is rising. "35"

[90LS400Lexus]

Yeah, it sounded like it was a short in your electrical wiring. How did you repair it?

It seems like this could be potentially dangerous. Has anyone ever heard of one of these catching fire? Typically when wiring shorts out, it overheats - or so I am told, but I have never heard of an LS having a fire near that shorted harness, but I suppose it is possible. Luckily, my 90' LS did not have this woe.

I have seen a few early LS400s with fires below the alternator. I suppose it is due to the faulty PS pumps leaking fluid onto the alternator and shorting it out.